Barcelona will host Real Madrid Tuesday in the second leg of the Copa del Rey semi finals, looking to advance to the final for the third consecutive season.

With the first leg finishing 1-1 in Madrid, Barcelona has the advantage heading into Tuesday’s match with an away goal in hand. The Catalan side has been nearly unbeatable at home over the past several years and with everything on the line, it would be hard to bet against them come Tuesday. However, Real Madrid has played well in tournaments this season, and while they have all but conceded the La Liga title, Jose Mourinho has his team poised and focused on Copa del Rey and Champions League play.

The first leg of the semi finals was a brilliant display of football with a rowdy crowd and some beautiful play. Both squads had multiple chances in the first half with Real Madrid coming the closest, but neither team could find the back of the net. The second half was a much different story as Cesc Fabregas scored within five minutes of the whistle and Barcelona looked to be in the drivers seat. For the next twenty-five minutes, Barcelona dominated play and while Madrid had some great chances, they couldn’t beat Victor Valdes.

It wasn’t until the 83rd minute that Madrid was finally able to strike, and it came in the form of an unexpected source as 19 year-old Raphael Varane sent a brilliant header passed the outstretched arms of Valdes and into the back of the net. The goal sent the home crowd into delirium and gave the team hope heading into the second leg.

Because both squads play such a possession-based style, it is often hard to pick key matchups. The ball moves so quickly that players often avoid tackles and both squads leave the one-on-one dribbling to select individuals. However, El Clasico puts on display some of the world’s best talent and there are always battles that change the outcome of the match.

Let’s take a look at some of the key players and key battles for Tuesday’s second leg semi final match:

Lionel Messi vs. Cristiano Ronaldo

Although these two players don’t often clash directly, the battle between the two best players in the world on one pitch is always key. Neither player scored a goal in the first leg; a rare occurrence, but both players had a significant impact on the match. Messi earned an assist on Barcelona’s first goal, while Ronaldo got into great scoring positions and caused chaos for Barca’s backline. Odds are that one of, if not both players will be involved in goals come Tuesday, but even without goals, these two players dazzle and delight with their individual skill and incredible ball control. Both Messi and Ronaldo have the ability to strike from free kicks and change the match as they attract double teams and earn fouls. There is no weakness for either player and it seems as if there is no answer on either side, which usually leads to fouls and scoring opportunities. While not a direct battle, the give and take from the world’s highest class is always a sight to see.

Andres Iniesta vs. Mezut Ozil

While Messi and Ronaldo usually grab headlines, maybe the next class of talent comes in the form of Andres Iniesta and Mezut Ozil. Iniesta, who finished third in Player of the Year voting earlier this year behind Messi and Ronaldo, has become arguably the best midfielder in the world. His awareness, touch, and vision lead to his ability to hold the ball against any opposition, no matter how strong or how fast. It is rare that Iniesta ever loses the ball or gives away a pass, and when he does it is usually a goal saving occurrence. Along with Xavi in the midfield, Iniesta is a pure genius when it comes to anything football and he is a main reason for Barca’s success in recent years. Real Madrid has a similar player in their midfield in the form of German Mesut Ozil. Ozil has come onto the world stage very quickly since joining Madrid and his craftiness, passing ability, and shot are unmatched by most. As a left-footed player, he often has defenders on their back foot and his deadly speed makes for a mismatch against almost every defender in the world. The battle between these two maestros is always fascinating to watch and will be key in Tuesday’s clash at Camp Nou.

Diego Lopez vs. Victor Valdes

These are usually the last names to be mentioned when talking about Real Madrid versus Barcelona, but this matchup could be the key to which teams moves onto the finals of the Copa del Rey. With Iker Casillas out injured, recent signing Diego Lopez will have to fill in the net with as much leadership as he can in such a big match. Having played well since his signing, Lopez can make the difference in a must win match in a hostile environment. Barcelona is bound to get chances and the question will be how well Lopez can play between the pipes. On the other side, Victor Valdes has been known as Barcelona’s “weak ink” for years, but he is no scrub. A short man with fiery leadership, Valdes often has trouble with the easy plays, but makes the most difficult of saves in the most crucial of times. Because both teams have such skilled players, there is probably going to be an onslaught on both nets and the keepers will have to shine if either squad is to move onto the final.